.card-thumbnail {
    position: relative;
    width: auto;
    height: 20em;
    overflow: hidden;
}
.page-header {
    padding-top: 20px;
    padding-bottom: 20px;
}

.page-footer {
    padding-top: 40px;
}
.card-thumbnail img.portrait {
    width: 100%;
    height: auto;
}
.card-thumbnail:hover {
    border: 5px solid transparent;
}

.card-thumbnail img {
    position: absolute;
    left: 50%;
    top: 50%;
    height: 100%;
    width: auto;
    -webkit-transform: translate(-50%, -50%);
    -ms-transform: translate(-50%, -50%);
    transform: translate(-50%, -50%);
}